EMIGALL object for updating not creating object instances

I am familiar with EMIGALL objects being used for creating business object instances / data objects in SAP ECC IS-U. ... But I don't recall an instance where I used it to update any data in ECC.... how should I get started with this?   I am very familiar with LSMW using BDC, BAPI, EDI, DI  -- direct input  -- for updating data....

Thanks!